Does the think-aloud protocol reflect thinking? Exploring functional neuroimaging differences with thinking (answering multiple choice questions) versus thinking aloud

Background: Whether the think-aloud protocol is a valid measure of thinking remains uncertain. Therefore, we used functional magnetic resonance imaging (fMRI) to investigate potential functional neuroanatomic differences between thinking (answering multiple-choice questions in real time) versus thinking aloud (on review of items). Methods: Board-certified internal medicine physicians underwent formal think-aloud training. Next, they answered validated multiple-choice questions in an fMRI scanner while both answering (thinking) and thinking aloud about the questions, and we compared fMRI images obtained during both periods. Results: Seventeen physicians (15 men and 2 women) participated in the study. Mean physician age was 39.5+7 (range: 32-51 years). The mean number of correct responses was 18.5/32 questions (range: 15-25). Statistically significant differences were found between answering (thinking) and thinking aloud in the following regions: motor cortex, bilateral prefrontal cortex, bilateral cerebellum, and the basal ganglia (p